Mongolian archers perform during the opening ceremony of the annual Naadam Festival in Ulan Bator July 11, 2011. Naadam is the biggest event in the Mongolian calendar held from July 11 to 13, on the anniversary of the Mongolian revolution of 1921. Concerts, fairs and traditional sports like wrestling, archery and horse racing are held during the celebration. REUTERS/Zeev Rozen (MONGOLIA - Tags: ANNIVERSARY SOCIETY)